Internal combustion engine



FIG. 1 is a top plan view of an internal combustion engine showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a perspective view from the left side-front thereof; and,

FIG. 8 is a perspective view from the right side-rear thereof. 

The ornamental design for an "internal combustion engine", as shown and described. 